It is our purpose in making this study to determine: 1) the site of the immunologic response to various corneal stimuli such as the injection of foreign proteins or the implantation of homografted tissues; 2) the type of immunologic response at the sites; 3) the onset, intensity, and duration of the immunologic response; and ultimately 4) the effect of various therapeutic agents; local, systemic or both, on this response. The Jerne plaque technique and the migration inhibition test will be employed to make these determinations.